When an app cannot be installed

The catalogue only shows apps your device can run, and some of them show a message instead of the install button. Each message has one cause.

Message	Why	What to do
"Requires Power Mode"	The app needs deeper access to the device. Devices start restricted.	Pi or Linux: unlock Power Mode in the device Settings tab. See Power Mode and system services.
"This device needs a connected camera"	A camera app, and the device reports no camera.	Plug in a supported camera, give the device a minute to report it, reload.
"This device needs a Wayland compositor" or "a preinstalled desktop (Chromium)"	Kiosk apps need a desktop on the device. Raspberry Pi OS Lite has none.	Use a Pi with the desktop edition of Raspberry Pi OS, or pick another app.
"Needs 4 GB RAM, this device has 2 GB"	Not enough memory.	Use a device with more memory. Some apps have a drop-down with smaller options; options the device cannot carry are greyed out.
"Needs 10 GB free disk, this device has 3 GB"	Not enough free space.	Remove apps you no longer use, or move to a bigger SD card or disk. On a Mac, use Expand storage in the Mac app.
"This device can't install anything yet. Open the Mac app and trust your management key, then come back."	The Mac does not trust your device key yet.	Open the Mac app, finish the trust step, come back and retry.

Apps that do not appear at all

Raspberry Pi exclusive apps (camera streaming, kiosk mode) are hidden on a Mac and on a Linux PC.
On a Mac, the Pi version of Ollama with Open WebUI is hidden. The Mac has its own "Mac AI" apps that run Ollama directly on the Mac.
Those Mac host services are installed once per Mac. While one is installed you cannot install a second copy. On Pi and Linux you can install several copies of the same app.
On a 32-bit system (armv7) no apps run at all. Reinstall with the 64-bit Raspberry Pi OS, see Which device?.